[show abstract][hide abstract] ABSTRACT: Abstract Native bees are important ecologically and economically because their role as pollinators fulfills a vital ecosystem service. Pollinators are declining due to various factors, including habitat degradation and destruction. Grasslands, an important habitat for native bees, are particularly vulnerable. One highly imperiled and understudied grassland type in the United States is the Pacific Northwest Bunchgrass Prairie. No studies have examined native bee communities in this prairie type. To fill this gap, the bee fauna of the Zumwalt Prairie, a large, relatively intact remnant of the Pacific Northwest Bunchgrass Prairie, was examined. Native bees were sampled during the summers of 2007 and 2008 in sixteen 40-ha study pastures on a plateau in northeastern Oregon, using a sampling method not previously used in grassland studies-blue vane traps. This grassland habitat contained an abundant and diverse community of native bees that experienced marked seasonal and inter-annual variation, which appears to be related to weather and plant phenology. Temporal variability evident over the entire study area was also reflected at the individual trap level, indicating a consistent response across the spatial scale of the study. These results demonstrate that temporal variability in bee communities can have important implications for long-term monitoring protocols. In addition, the blue vane trap method appears to be well-suited for studies of native bees in large expanses of grasslands or other open habitats, and may be a useful tool for monitoring native bee communities in these systems.
Journal of Insect Science 01/2012; 12:108. · 0.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: The western bumble bee, Bombus occidentalis, is included on the red list of bees by The Xerces Society. It was once a common bumble bee west of the Cascades but in the late 1990s it experienced a dramatic decline along coastal regions. The cause was speculated to be due to the introduction of pathogens from captive-bred bumble bees used for pollination of greenhouse crops. In extensive surveys conducted in western and southern Oregon, 10 individuals have been recorded since 2000. In this note, we report the collection of 49 individual B. occidentalis over two years in the Zumwalt Prairie Preserve of northeastern Oregon. This finding shows that B. occidentalis persists in northeastern regions of the Pacific Northwest, either because of geographic isolation from or potential resistance to the pathogens that decimated populations in the western part of the region. Further research is needed to determine its occurrence in other regions of its historical range to assess the extent of its decline. In addition, conservation efforts are critical for protection of this species in both agricultural ecosystems and in native habitats.
[show abstract][hide abstract] ABSTRACT: Many cranberry growers on the Oregon coast are well aware that good pollination is necessary for quality fruit set. Multiple visits to the flower deliver more pollen, which can increase the percentage fruit set, number of seeds per berry, and mature berry weight. The better a bee is at delivering pollen to the flower, the fewer the number of visits required for adequate pollination. Typically growers rent hives of the European honeybee for cranberry pollination. However, honeybees have exhibited a general preference for lotus, gorse, other weeds and native plants over cranberry flowers. As a result, growers must bring in enough hives to saturate the surrounding area so that at least some of the honeybees will have no choice but to forage in cranberry beds. In addition, honeybees forage primarily in fair weather. Multiple studies have shown (and many people have observed) that honeybees will retreat to their hives once it begins to rain. Often, they will retreat even when the skies become overcast, which is not ideal behavior for working in stormy coastal weather. Further, with the recent concerns about Colony Collapse Disorder, attack by mites and other diseases, the supply of available hives has decreased. This shortage brings to light the need for an alternate pollinator—a native species that is not susceptible to the ills of honeybees. In the Pacific Northwest, there are over 200 species of native bees. Those species native to Oregon are acclimated to Oregon weather. Several species of bumblebees begin foraging hours before honeybees are active, and cease foraging at dusk when the honeybees have already been inactive for an hour or two. The advantages of having bees forage longer hours are obvious—the more time they spend foraging, the more flowers they will pollinate. In addition, Oregon's native bee species are often sighted foraging when it is drizzling while the warm-weather preferring honeybees are in their hives. Currently, little is known about the number and diversity of bee species present on the southern Oregon coast. This information is required for determining whether a better pollinator than honey bees is available for cranberries. By determining which species are present during bloom it will be possible to select a species that flies during bloom, and one that is also loyal to cranberries.